JPH07242033A - Printer - Google Patents

Abstract

PURPOSE:To provide a printer reduced in the number of parts for judging whether the type of a type wheel is positioned at a printing position and simplified in control operation for judgment. CONSTITUTION:A control means 22 judges the origin position of a type wheel 10 on the basis of the detection signal of an origin sensor 20A detecting the origin display part 14A provided at the position corresponding to the origin position of the type wheel 10 of the rotary shaft 12a of a stepping motor 12 and judges whether the type of the type wheel 10 is positioned at a printing position on the basis of the exciting signals phi1-phi4 exciting the excitation phase of the stepping motor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention rotates a type wheel, stops the type wheel when a predetermined type on the type wheel is positioned at a printing position, and prints a medium with a printing hammer through an ink ribbon. The present invention relates to a printing device that performs a printing operation by tapping on.

[0002]

2. Description of the Related Art Conventionally, there is a printing apparatus which selects and prints a desired character by controlling the rotation of a character wheel having a plurality of characters. Such a printing device is shown in FIG.
The configuration is as shown in. That is, a plurality of print characters, for example, 10 print characters (not shown) of “0” to “9”, on the outer peripheral surface of the print wheel 10 which is a flat cylinder, are arranged on the central axis of the print wheel 10. It is formed as a center for each predetermined rotation angle.

The upper part of the rotary shaft 12a of the stepping motor 12 is coupled to the center hole 10a of the type wheel 10, and the type wheel 10 is rotated by an arbitrary rotation angle by a drive signal given to the stepping motor 12. It has become so. A disc-shaped detection plate 14 is coupled to the lower portion of the rotary shaft 12a to detect the rotation angle of the rotary shaft 12a.

As shown in FIG. 5, the detected plate 14 is formed with a character slit S corresponding to the position of the character formed on the character wheel 10 on the same circumference. When one of the plurality of characters of the character wheel 10 is positioned at a predetermined position (printing position) facing the print hammer 16, the character slit S corresponding to the character is a character position sensor that is a transmissive optical sensor. It is detected by 18.

Further, the detected plate 14 has an origin slit Sg formed on a circumference having a radius different from the circumference on which the type slit S is formed. This origin slit Sg
Is detected by the origin position sensor 20 which is a transmitted light type optical sensor when the type wheel 10 is positioned at the origin position.

An ink ribbon (not shown) is previously arranged between the type wheel 10 and the paper P. Type wheel 10
The desired character is positioned at a position facing the print hammer 16 by rotating, and the print hammer 16 is repelled in the direction of arrow F by a well-known drive mechanism. This allows
The paper P is impacted against the ink ribbon and the printed characters by the pressing force of the print hammer 16, whereby the ink is attached by the printed characters and the printing operation is performed.

The operation of selecting a character type in such a printing apparatus is as follows. That is, when the power is turned on, the stepping motor 12 is rotated to rotate the type wheel 10, and the origin position sensor 20 detects the origin slit Sg of the detection target plate 14 to confirm the origin position of the type wheel 10. Next, the rotation angle of the type wheel 10 required for printing with a desired type is determined with the origin position as the reference position. By rotating the stepping motor 12 based on the drive pulse signal of the number of steps corresponding to the rotation angle, the character to be printed on the character wheel 10 is positioned at the printing position.

At this time, it is necessary to confirm whether or not the character to be printed on the character wheel 10 is positioned at the printing position. This confirmation operation is performed as follows. That is, when positioning a desired character at the printing position, the number of character slits S to be detected by the character position sensor 18 when moving the character wheel 10 from the reference position (origin position) to a predetermined position ( The reference count value) is obtained in advance. Next, when the detected plate 14 is actually rotated, the number of the character slits S (actually counted value) detected by the character position sensor 18 is counted by a counter or the like. Then, the reference count value and the actual measurement count value are compared, and if the two match, it is determined that the desired character is positioned at the print position,
If they do not match, it is determined that the positioning has failed. That is, since the number of the character slits S detected by the character position sensor 18 corresponds to the rotation angle of the character wheel 10, whether or not the character wheel 10 is correctly positioned is determined by the count value of the character slit S. It can be determined based on.

When the type selection operation is continued after the type selection operation and the printing operation described above are completed,
A type selection operation similar to that described above is performed using the position of the type wheel 10 at the end of the above operation as a reference position.

[0010]

The conventional device as described above has the following drawbacks. (A) Type position sensor 18 for detecting type slit S
And the origin position sensor 20 for detecting the origin slit Sg must be separately provided. Therefore, the sensor
It requires individual parts and costs parts. In addition, the manufacturing cost is high because the number of steps for mounting and adjusting the two sensors is large. (B) Since the inertia moment increases due to the weight of the detected member coupled to the rotation shaft of the stepping motor, the positioning accuracy of the rotation shaft of the stepping motor deteriorates. (C) The control operation is complicated because the reference count value and the actual measurement count value are compared and determined every time the success or failure of the positioning of the type wheel is determined based on the count value of the type slit S. The present invention has been made based on such circumstances,
The purpose is to use one sensor to identify the position of the typeface.
To provide a printing device that can detect only a minimum number of members to be detected, and that can determine whether or not a character to be printed on a character wheel is positioned at a printing position by a simple control operation. is there.

[0011]

A printing device of the present invention is a stepping motor in which a printing wheel is rotated by a stepping motor until a printing character of the printing wheel faces a predetermined printing position. The origin display part provided at a position corresponding to the origin position of the type wheel on the rotation axis of, the origin sensor that detects the origin display part, and whether or not the type to be printed on the type wheel is positioned at the specified print position. Is provided based on an excitation signal for exciting the excitation phase of the stepping motor. Further, the origin display portion may be provided on the type wheel.

[0012]

The origin position of the type wheel is identified by detecting the origin display section by the origin sensor. Whether or not the type to be printed on the type wheel is positioned at a predetermined printing position is determined by the control means based on the excitation state of the excitation phase of the stepping motor, that is, based on the excitation signal for exciting the excitation phase. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of essential parts showing an embodiment of a printing apparatus of the present invention, FIG. 2 is a control block diagram in the embodiment, and FIG. 3 is a flow chart of control operation. In FIGS. 1 and 2, members that are the same as or correspond to those in FIGS. 4 and 5 showing the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, a rotary shaft 12a of the stepping motor 12 is provided with an origin display section 14A. The origin display portion 14A is provided at a position corresponding to the origin position of the type wheel 10. This origin display section 14A
An origin sensor 20A is arranged to detect the. The origin sensor 20A detects the origin display portion 14A and outputs a detection signal when the type wheel 10 is at the origin position. The origin display unit 14A is, for example, a protrusion provided in a direction perpendicular to the rotary shaft 12a, and the origin sensor 20A is used.
May be configured by a transmissive or reflective photosensor or a microswitch that is turned on by the protrusion.

In FIG. 2, the input section 21 converts character information supplied from a keyboard or an external device (not shown) into a predetermined control signal and supplies it to the control means 22 in the next stage.
The control means 22 includes a well-known central processing unit (CPU), a ROM for storing a control program, a RAM for temporarily storing various data, a well-known interface circuit, etc. (none of which are shown). , And is connected to the port 24 via the bus B. The control unit 22 controls and executes the printing operation described later based on the control signal.
In addition, the control unit 22 causes the display unit 25, which is an arbitrary display device, to perform various display operations so that the user of the printing apparatus can recognize the operation state. The control table unit 23 uses the number of steps of the stepping motor 12 when the type wheel 10 is positioned at the origin position as a reference position, and the number of steps of the stepping motor 12 required to position each type of the type wheel 10 at the printing position. Is stored in correspondence with each type, and is provided in a storage area such as a ROM. Control means 22
Is a control table unit 23 that indicates the number of steps corresponding to each type of character determined according to the character information given from the input unit 21.
It is designed to read from.

In this embodiment, the stepping motor 12 has four exciting phases, that is, A phase, A bar phase,
A case will be described in which a two-phase stepping motor having a B-phase and a B-bar phase is used and is driven by a two-phase excitation method.

The control means 22 includes the stepping motor 12
In order to drive the motor by the intended rotation angle, the drive pulse signal PS corresponding to the number of steps corresponding to the rotation angle is given to the motor control means 26 via the port 24. The motor control means 26, based on the applied drive pulse signal PS, the excitation signals φ1 to φ4 corresponding to the above four excitation phases.
Is generated and given to the motor drive means 28. The motor drive means 28 supplies a drive current (excitation current) Id to the stepping motor 12 according to the applied excitation signals φ1 to φ4.
The stepping motor 12 is rotationally driven by supplying it to the winding of each excitation phase.

Excitation signals φ1 to φ corresponding to four excitation phases
4 is supplied to the motor drive means 28 and also input to the port 24. The control unit 22 can determine the valid state of each excitation phase by identifying the states of the excitation signals φ1 to φ4 via the port 24.

Table 1 is a correspondence table showing the correspondence between the excitation signal and the step number when the stepping motor 12 is rotationally driven by the two-phase excitation method, and the step number is from 1 to 12. Two excitation signals are always valid (indicated by black circles) for one step of the stepping motor 12. That is, each time the stepping motor 12 is driven to rotate by one step, the exciting current is sequentially supplied to the stator windings corresponding to the two adjacent exciting phases, so that the two exciting phases are sequentially excited. .

[Table 1]

The type wheel 10 is set so that the excitation state of the stepping motor 12 becomes the same when the type of the type wheel 10 is positioned at a predetermined printing position. That is, the above-mentioned type is formed in the type wheel 10 for each rotation angle corresponding to the number of steps such that the excitation state of the stepping motor 12 is the same.

As an example, the type in the type wheel 10 is 4
A case will be described in which each rotation angle is formed for each step. That is, the print characters are provided at the rotation angle positions corresponding to steps 1, 5 and 9 shown in Table 1. Here, when the type wheel 10 is positioned so that the type at the rotation angle position corresponding to step 1 in Table 1 comes to the predetermined printing position, the excitation signal φ of the stepping motor 12 is generated.
1, φ4 becomes valid. Next, when the stepping motor 12 is rotationally driven by one character of the type wheel 10, that is, by four steps to reach the rotation angle position corresponding to step 5, the excitation signal φ1,
φ4 becomes valid. Similarly, stepping motor 1
2 for n characters of the type wheel 10 (n is an integer), that is, 4n
When only the steps are rotationally driven, the excitation signals φ1 and φ4 are in the valid state as before the driving.

That is, when the characters on the character wheel 10 are positioned at their respective printing positions, the same excitation signal is always in the valid state. Therefore, the control means 22
In response to the character information from the input section 21, the type wheel 10 is rotated when the type wheel 10 is driven to rotate and a predetermined number of pulses for positioning a desired type character at the printing position are given to the motor control means 26. It is possible to confirm whether or not the desired type of character is positioned at the print position based on whether or not the same excitation signal is in the valid state. That is, the control unit 22 can determine and confirm the success or failure of the positioning of the type wheel 10 based on the state of the excitation signal.

In the excitation method as shown in Table 1, the rotation angle intervals of the characters formed on the character wheel 10 (hereinafter referred to as the inter-character angle) are limited to those corresponding to the above-mentioned four steps. Instead, the rotation angle interval may correspond to a step of an integral multiple of 4. That is, the number of steps may be 8, 12, 16, ... Therefore, the angle between the typefaces of the typeface 10 depends on the number of typefaces and the typeface 1.
It can be appropriately set according to the size of 0.

Further, the combinations of the excitation signals that become effective when the type of the type wheel 10 is positioned at the printing position are limited to the combinations of φ1, φ4 (steps 1, 5, 9) shown in Table 1. is not. Excitation signal φ1, φ2
Any combination of (steps 2, 6, 10), excitation signals φ2, φ3 (steps 3, 7, 11) and excitation signals φ3, φ4 (steps 4, 8, 12) may be used.

Next, the printing operation of the printing apparatus having the above construction will be described with reference to the block diagram of FIG. 2 and the flowchart of FIG. The paper is sucked by the paper transport mechanism of the printer and set at a position where printing can be performed (step P1).

Next, the type wheel 10 is rotationally driven and positioned at the origin position (step P2). That is, the control means 22 gives the drive pulse signal PS for rotating the stepping motor 12 by a predetermined angle to the motor control means 26 via the port 24. The motor control means 26 supplies the excitation signals φ1 to φ4 to the motor drive means 28 based on the drive pulse signal PS, whereby the drive current Id is supplied from the motor drive means 28 to the stepping motor 12 to rotate the rotary shaft 12a. . Origin sensor 20A
Indicates the detection signal D by detecting the origin display portion 14A.
To the control means 22 via the port 24. As a result, the control means 22 determines that the type wheel 10 is at the origin position, and gives the drive pulse signal P to the motor control means 26.
By stopping S, the rotation of the stepping motor 12 is stopped. As a result, the type wheel 10 is stopped at the origin position.

The control means 22 stores the character information in a storage means such as a RAM based on a control signal from the input section 21 which has received the character information to be printed (step P3).

Next, the control means 22 reads the character information for one character from the storage means (step P4).

Then, the control means 22 reads the number of steps corresponding to the type of the read character from the control table section 23. Then, based on the read step number and the step number (current step number) at the current stop position of the stepping motor 12, the step of the stepping motor 12 necessary for positioning the type of the character just read at the print position. Calculate and determine the number (step P
5).

Next, the control means 22 gives the rotation control signal PS corresponding to the determined number of steps to the motor control means 26. As a result, similarly to the above, when the driving current Id is supplied, the stepping motor 12 is rotated by the rotation angle corresponding to the number of steps and is stopped and positioned (step P6).

Here, the control means 22 determines whether or not the type wheel 10 is accurately positioned based on the excitation signal (step P7). That is, the excitation signals φ1 to φ1 supplied from the motor control means 26 to the motor drive means 28.
φ4 is input via the port 24, and the actual valid state of the excitation signal and the preset valid state of the excitation signal when the character of the type wheel 10 is positioned at the print position are compared and collated to determine the success or failure of the positioning. judge.

If step P7 is affirmative, as shown in FIG. 1, the printing hammer 16 is repelled to execute the printing operation for one character on the paper P (step P8).

Next, the control means 22 temporarily stores the number of steps of the stepping motor 12 at that time in a storage means such as RAM (step P9), and with respect to all the character information stored in step P3. It is determined whether the printing operation on the paper is completed (step P1).
0). If the result in step P10 is affirmative, the paper is ejected (step P11). Then, the stored current step number of the stepping motor 12 is cleared and the operation ends (step P12). This clearing operation is a preparatory operation for executing the printing operation for the next sheet. If the result in step P10 is negative, the paper is conveyed in the printing direction for a predetermined distance (step P13), the process returns to step P4, the character information to be printed next is read, and based on the current step number of the stepping motor 12 at that time. Calculate the number of steps to drive the stepping motor 12,
A similar positioning operation of the type wheel 10 is performed.

On the other hand, if the result in step P7 is negative, the retry operation, that is, the printing wheel 10 is positioned at the origin position and the same operation as in steps P4, P5 and P6 is performed again (step P14). This retry operation is performed to prevent the printing apparatus from stopping, and is performed a predetermined number of times, for example, three times, until it is determined that the type wheel 10 has been rotated by the intended rotation angle.

Then, the control means 22 determines whether or not the type of the type wheel 10 has been positioned at the printing position by the above retry operation, that is, whether or not the retry has succeeded (step P15). If the result in step P13 is affirmative, the process proceeds to step P8. If the result is NO in step P14, the printing operation is stopped and the fact is displayed on the display means 25 by a predetermined display method to notify the user (step P16). The printing operation is stopped and the process proceeds to step P11. After shifting, the sheet is discharged (step P11), the step number of the stepping motor 12 at that time is cleared, and the operation is ended (step P12).

In the above-mentioned operation, if the type wheel 10 becomes unrotatable for some reason while the type character is positioned at the printing position, this cannot be detected. Therefore, in practice, the origin sensor 20A changes the origin display unit 14 every time the printing operation is performed once or every predetermined number of times.
The rotation shaft 12a is rotated so as to detect A, and the control means 22 constantly monitors the rotation state of the type wheel 10 based on the detection signal of the origin sensor 20A.

According to the above-mentioned embodiment, the transmission type optical sensor is used as the origin sensor 20A constituting the origin sensor, but a reflection type optical sensor may be used. Further, in this embodiment,
The origin display portion 14A is used as the rotary shaft 1 of the stepping motor 12.
Although it is provided in 2a, the origin display section is the origin sensor 20A.
Anything that can be detected by, for example, the rotating shaft 12a
It may be a pin-shaped member that is provided so as to project. Rotating shaft 12
A disc-shaped detection plate may be coupled to a, a transmission part such as a slit or a hole may be provided in this detection plate, and the transmission part may be used as an origin display part for detection by the origin sensor 20A.

The origin display section may be provided on the type wheel 10. For example, a through-hole may be provided in a direction parallel to the rotation axis of the type wheel 10, and the through-hole may be used as an origin display section for detection by the origin sensor 20A. In addition, a protrusion or a pin may be provided as an origin display portion on a part of the type wheel 10 and detected by the origin sensor 20A.

In this embodiment, the case where the two-phase stepping motor 12 is driven by the two-phase excitation method has been described, but the number of phases of the stepping motor may be other than two, and the excitation method other than the two-phase excitation method. You may drive with. In addition, in the present embodiment, the position of the type wheel 10 when the type of the type wheel 10 is positioned at the printing position corresponds to one excitation state (for example, the excitation signals φ1 and φ4 are effective). However, for each of a plurality of excitation states (for example, the excitation signals φ1 and φ4 are valid, and the excitation signals φ2 and φ3 are valid), the type wheel 10 when the type wheel 10 is positioned at the printing position. The positions may correspond.

According to the present embodiment described above, the type wheel 1
The origin position of 0 is determined by detecting the origin display unit 14A by the origin sensor 20A (origin sensor). Further, it is determined by the control means 22 based on the excitation state of the excitation phase of the stepping motor 12, that is, the excitation signals φ1 to φ4 for exciting the excitation phase whether or not the type of the type wheel 10 is positioned at the printing position. . Therefore, as a sensor for detecting the position of the type wheel 10,
Since it is only necessary to provide one set (one) of the origin sensor 20A, not only the number of parts can be reduced, but also the number of steps for mounting and adjusting the parts can be reduced. In addition, the origin display unit 14
A needs only to have a minimum size, as long as the position can be detected by the origin sensor 20A. For this reason,
Since the origin display unit 14A does not adversely affect the moment of inertia of the stepping motor, the positioning accuracy of the rotary shaft of the stepping motor becomes good. The success or failure of the positioning of the type wheel 10 can be determined by a simple control operation based on the excitation state of the excitation phase of the stepping motor 12, that is, the excitation signal.

[0041]

As described above in detail, according to the printing apparatus of the present invention, since only one sensor for detecting the position of the printing wheel is required, not only the number of parts is reduced but also the mounting of the detection sensor and It requires less man-hours for adjustment. Further, since the member to be detected that affects the moment of inertia of the stepping motor is not provided, the positioning accuracy becomes good. Since the success or failure of the positioning of the type wheel is determined based on the excitation state of the excitation phase of the stepping motor, the control operation associated with the determination becomes simple.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of essential parts showing an embodiment of a printing apparatus of the present invention.

FIG. 2 is a control block diagram in the embodiment.

FIG. 3 is a control flowchart of a printing operation in the embodiment.

FIG. 4 is an exploded perspective view of essential parts showing an example of a conventional printing device.

FIG. 5 is a plan view of a detected plate in a conventional printing device.

[Explanation of symbols]

 10 type wheel 12 stepping motor 12a rotating shaft 14A origin display 22 control means 20A origin sensor φ1 to φ4 excitation signal

Claims (2)

[Claims] 1. A printing device for performing a printing operation by rotating a type wheel by a stepping motor until a type character to be printed on the type wheel faces a predetermined printing position, wherein a printing wheel is provided on a rotation shaft of the stepping motor. An origin display unit provided at a position corresponding to the origin position, an origin sensor for detecting the origin display unit, and a stepping motor for determining whether or not a character to be printed on the character wheel is positioned at the predetermined printing position. And a control unit for making a determination based on an excitation signal for exciting the excitation phase of the printing apparatus. 2. The printing apparatus according to claim 1, wherein the origin display portion is provided on the type wheel.